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    Computer Networks

    Need for computer communication Networks:An employee of an organisation who has PC at home would use it for most of his work and connect it through communication lines to apowerful computer called a server fro executing larger programs and to access soecial library programs and data resident in the server for executing large programs and accss special library programs and data resident in the server situated in the organizations.
    Internet and The World Wide web:Electronic mail is an application in which any user on a network can send/recieve letters using his computer terminal to/from any person in the world who has an ewlectronic mail address Internet provdes a worldwide electronic mail facility.
    File transfer: Mail is intended for short mesages.A file transfer program is available on the internet which allows transferring a large file containing programs or data from a computer in any part of rthe world another.The rule used in internet for file transfer is called file transfer protocol or ftp for short.
    Remote Login:By remote login or telnet access we mean a user sitting on his terminal logging on to a machine located anywheren in the world.Remote login allows a user workstation or PC to behave as through it is directly connected to the machine the user is logged in.
    World Wide Web:Information is normally dispersed over many computers connected to the internet.If the a user wants to obtain information from any of these computers they must be logically linked.The information stored in computers is not only text but also graphics(images),sound and vedio.This is callled multimedia information.All web pages are addressed starting with http.
    Local Area NetworksWhen computer located within small geographical area such as office or a university campus(within a radius of 10km)are connected together e call it LAN.
    Metropolitian Area NetworksIt is the area which is connected within the city or area of around 100 km radius at speed betyween between 56kbps and 155 mbps depending on the technology used such as internet or leased lines.
    Wide Area NetworkIt is connected with allover the world in which also known as long haul networks, operate over tthe entire world with speeds in the range 9.6kbps to 156 mbps.

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